Energy Systems

3 primary energy systems

1, phosphagen (ATP/PCR)

2, glycolytic system

3, oxidative system

energy system used at start of exercise

phosphagen (ATP/PCR)

energy system used around 60 second mark of exercise

glycolysis system

energy system used at 120 seconds of exercise

oxidative system

metabolism

all chemical processes in living organisms require metabolism for the maintenance of life

2 phases of metabolism

anabolism and catabolism

anabolism

smaller molecules are converted to larger molecules

EX: glucose to glycogen

catabolism

larger molecules are broken down to smaller molecules

EX: triglycerides to glycerol/ fatty acids

mitochondria

• found in every cell in human body except red blood cells

• membrane bound structure

• where krebs cycle and ETC happen

krebs cycle

series of chemical reactions that produce a larger quantity of ATP

ATP

• energy currency of cells

• catabolic reactions convert biochemical energy from organic molecules to ATP

cell respiration

controlled release of energy in form of ATP

Structure of ATP

triphosphate group - 4O + P

adenosine group - sugar and base

Structure of ATP info

• bonds between three phosphate group are very energy rich

• energy is released when ATP combined with water

energy function in sports

required for muscular contraction

carbohydrate metabolism

the breakdown of carbohydrates into simple sugars like glucose, fructose, sucrose

glycolysis

breakdown of glucose to pyruvate

gluconeogenesis

lactase is transported back to liver when glucose is re-formed

glycogenesis

grouped together to form glycogen which can be stored in liver and muscles

glycogenolysis

process of glycogen release and breakdown to be used as glucose and glucose-6-phosphate in muscles

Carbohydrate metabolism graph

negative feedback loop

1, glucose absorbed after meal

2, pancreas responds to elevated glucose by secreting insulin

3, insulin causes liver, skeletal muscle, and other tissue to take more glucose

4, normal glucose level reached

aerobic energy systems conditions

• pyruvate is decarboxylated to form Acetly-CoA which produces ATP

• Oxygen and fuel not always available

anaerobic condition

pyruvate reduced to lactate which is an important source of ATP for cells without mitochondria

Pyruvate

chemical compound that is produced during the metabolism of glucose through glycolysis process

fat oxidation

1, fatty acids transported with help from enzyme carnitine

2, fatty acids broken down to Acetly-CoA

3, oxidation of fatty acids involves repeated cycle of 4 reactions where fatty acid chain reduced by 2 carbons each cycle

4, This produces energy

fat oxidation differences

the process could differ depending on

• chain length of fatty acid

• double or single bond

• how many double bonds

body preference in fats

body prefers to use mono and poly unsaturated fats than saturated fats

unsaturated fats bonding

monounsaturated fats have 1 double bond between two carbon atoms

polyunsaturated fats have 2 or more double bonds between two carbon atoms

saturated fats bonding

all carbon atoms connected by single covalent bonds

unsaturated fats

• one or more double bonds between C atoms

• liquid at room temp

• from plant source

saturated fats

• solid at room temp

• linear and compact structure

• single bonds between C atoms

• From animal sources

Cis - unsaturated

• naturally occuring

• H atoms same side as C=C bond

• causes kink in fatty acid chain

Tran-unsaturated fats

• result of food processing

• H atoms on opposite side of C=C bond

• Causes straighter fatty acid chain

adipose tissue

• just below skin fat

• cell that stores fats in form of tryglycerides

• functions: store energy and heat insulation

overconsumption of fat

body will store fat in adipose tissue and skeletal muscle

lypolysis

process of releasing triglycerides from body’s fat storage

Krebs cycle and ETC

Stages of aerobic metabolism which produce ATP with oxygen and fuel available

ETC

• happens in mitochondrial matrix and uses NADH and FADH which are 2 molecules created during krebs cycle and glycolysis

• ETC creates proton gradient leading to ATP production

Stages of cell respiration

1, glycolysis

2, oxidative decarboxylation

3, krebs cycle

4, ETC

5, oxidative phosphorylation

anaerobic energy systems

• phosphagen system

• glycolytic system

phosphagen system

• creates ATP

• cannot be used to drive muscle contraction

• formula = PCr + ADP = ATP + Cr

glycolytic system

• pyrvuate converted to lactate

• makes small amount of ATP

• process occurs quickly

• suitable for exercise lasting 20 seconds to a few minutes

• Formula = Glucose = 2ATP + 2Pyruvate = 2lactate + 2Hpositive

hormones in energy metabolism

• insulin

• glucagon

• epinephrine

• cortisol

• growth hormones

insulin response (after eating)

1, facilitates glucose intake into skeletal muscle and liver cells

2, promotes glycogen synthesis

3, inhibits glycogen breakdown

4, supports protein synthesis

Glycagon and epinephrine response (during fasting/exercise)

when blood glucose levels drop then pancreas releases glucagon which

• stimulates glycogen breakdown

• promotes glucose synthesis

• encourages fat breakdown

• enhances protein breakdown

Epinephrine enhancing effects ensuring a continued energy supply

Lactate inflection point

• the point where blood lactate begins to substantially accumulate above resting concentrations during exercise of increasing intensity

Lactic acid

• once exercise exceeds the rate of maximal oxygen consumption then an oxygen debt occurs and metabolism switches from aerobic to anaerobic which leads to increase in blood lactate levels

• increase in blood lactate impairs muscle contraction and leads to fatique and exhaustion

Critical power threshold

• measure of the maximum power output that a person can sustain for a prolonged period of time without becoming exhausted

Excess post-exercise oxygen consumption

• when the body gets into an oxygen deficit because oxygen need and oxygen supply does not match in the first moment of exercise

• during recovery from exercise, oxygen utilisation continues at greater rate than needed at rest

Two components of excess post-exercise oxygen consumption

• fast component which represents oxygen required to rebuild the ATP and PCr used during the initial stages of exercise

• Slow component which represents the result of the removal of lactate from the muscle tissues, either by conversion to glycogen or oxidation to CO2 and H2O which provide energy required to restore glycogen stores

Reasons why oxygen consumption remains elevated during recovery from exercise

• oxygen is required to rebuild the ATP and PCr stores

• respiration remains elevated to help clear out any excess CO2 from tissues

• oxygen must be replenished to haemoglobin and myoglobin which was taken during exercise